Representing electrical behaviour of transformers by lumped element circuits: a global physical approach

Abstract

This paper proposes equivalent circuits to represent the external electrical behaviour of multiwinding transformers. All aspects of the linear behaviour, including resonances and inter-winding devices to currents, are taken into account. The global physical components approach leads to general lumped element circuits such that only element values change from one component to another. All the element values of the proposed circuits are deducible from external electrical measurements with no need for extra information regarding shape, size, used technology and, even, turn numbers. This paper includes two parts. The first one focus on the representation of linear loss free magnetic coupling. How to represent leakage of multi-winding transformers and what measurements to choose to fully and accurately characterise magnetic coupling are among the investigated subjects. In the second part, representation of stray capacitors is studied: how to represent the electrostatic behaviour of multi-winding transformers and what measurements to choose to fully and accurately characterise these components.